The present invention relates in general manner to measuring temperature in turbomachines, and it relates more particularly to measuring temperature in wound elements such as transformers or inductors arranged in a housing in the environment of an engine (fan casing of an aeroengine) where the temperature of the housing must not exceed 204° C. in the event of a single failure (e.g. resulting from an electrical short circuit), which temperature is generally taken as being the self-ignition temperature of fuel vapors.
A winding of a wound element is an extremely heterogeneous combination made of copper, insulating films, resins, air, . . . . Furthermore, for reasons of electrical functionality, windings are made up of layers of turns that are extremely compact. Measuring temperature within such a wound element is thus found to be particularly difficult.
At present, two measurement methods can be distinguished. The first method, which is used mainly in the windings of rotary machines, consists in introducing temperature probes directly into the cores of wound elements. That requires having recourse to a winding method that is quite complicated in order to avoid damaging the probe without giving rise to unacceptable leakage inductance in order to achieve good electrical performance, and the level of losses nevertheless remains quite high.
The second method, which is used more particularly in the inductors and transformers of electricity networks, which components are particularly sensitive to leakage induction, consists either in bonding temperature probes onto the wound elements after they have been made, or else in encapsulating the probes in blocks of resin that are inserted between the wound elements. Nevertheless, bonding involves an additional industrial step that is particularly difficult, while encapsulation firstly involves putting the probe into position, which cannot be done accurately during encapsulation, and secondly can lead to failures not being detected because of the poor thermal conductivity of resins, which causes such temperature probes to have a response time that is very long.
There thus exists at present a need to find means that are simple from an industrial point of view for recovering temperature information rapidly from a winding without degrading its electrical performance.